The present invention relates to a finisher for use with a copier, printer or similar image forming apparatus and operable to sort recording sheets, or paper sheets, sequentially driven out of the apparatus by shiting them or otherwise finish such paper sheets.
Finishers for use with an image forming apparatus include one which delivers paper sheets sequentially driven out of the apparatus to shiftable tray and shifts and thereby sorts them volume by volume on the tray. In this type of finisher, the tray for collecting the paper sheets is shifted by sorting means in a horizontal plane in a direction perpendicular to an intended direction of paper discharge. Each paper sheet discharged onto the tray is positioned in a direction perpendicular to an intended direction tray shift by the positioning member, i.e., at the trailing edge thereof and then shifted.
The problem with the conventional finisher described above is that he positioning member remains in contact with the top of the paper stack loaded on the tray and, therefore, interferes with the shift of the tray. Specifically, the positioning member dislocates the paper sheets neatly stacked on the tray when the tray is caused into a shifting motion. It is likely that the paper stack is dislocated not only in the intended direction of tray shift but also in the direction perpendicular thereto. To eliminate this problem, the discharge tray may be shifted while being moved in the up-and-down direction, as proposed in the past. However, such a movement of the tray is not reliable and not practicable without resorting to a complicated mechanism.